Darting behavior of a sandburrower fish,Limnichthys nitidus (Creediidae), in the Red Sea

Synopsis

Creediid fishes usually live burrowed in sand. When disturbed they make quick movements out and back into the sand. The darting behavior of 35 individualLimnichthys nitidus was recorded on videotape with the aid of SCUBA in the shallow bay, Marsa Muqabelah, Egypt, on the NE coast of Sinai in the Gulf of Aqaba, Red Sea. Thirty-nine sequences show that these fish travel distances of 26.7 to 110 mm in a single dart (1.7 to 5.5 times their total length), can reach speeds of nearly 0.5 m per sec, and execute turns up to 185° to avoid objects in their path. The darting movements, size and cryptic coloration ofL. nitidus make them difficult to see yet they may be the most numerous fish in shallow sandy areas of the Red Sea reaching concentrations of over 50 m^-2, a density exceeded in chordates only by the lancelet,Branchiostoma caribaeum. Their population in Marsa Muqabelah was drastically reduced, along with that of other sand fishes, between 1987 and 1989 when the sand became mostly covered with an overgrowth of algal mats and sea grasses.